Science Buddies: "Ask an Expert"

I am doing this project(Electrolyte Challenge) from Science Buddies https://www.sciencebuddies.org/science- ... p053.shtml

Well I have two questions:
1) As for the conductance sensor, do I need to use a thing which is hollow and open AT BOTH ENDS? or using something which is non conducting but open at only end will suffice?

2)This is the serious part. I am not getting readings on my mutimeter. Well I checked the connections and my multimeter and everything else seems to be working fine. But when I checked the copper wires, it seemed they are not conducting any current. To check it, I connected the copper wires to the cell electrodes and the other end to the multimeter, my multimeter showed zero reading whereas in any other case it is giving me a normal reading of 9V for the cell. I could only conclude the copper wires are not conducting any current from the cell to the multimeter for it to measure. I know this is bizarre and even I am puzzled but i am not sure what is happening.

I also tried to measure the conductance of the solution using ohmmeter mode of multimeter but again the reading was one(as should be in an open circuit) and around 0.09 when i directly touched the test leads of the multimeter to each other.

So I would like to ask if there is any substitute. Can I remove the insulation off of normal connecting wires and use them in place of the copper wire? Please suggest.

souro - This is a pretty straight forward setup. As for the sensor, the coil can be 'free standing' if it is made of fairly stiff copper wire, say 18 gauge or larger. Any form it is wound on is only to provide mechanical stability. It could be hollow or solid, as long as it isn't a conductor. The only important consideration is that the surface area of the copper wire coil is in contact with the liquid. Obviously this is bare copper wire. Some copper magnet wire have a thin enamel insulating layer that can make the wire appear to be 'bare' but it is still insulated by a very thin layer of enamel. If in doubt, scrape it with a knife or strip it with fine sandpaper.

If you have access to any 100-to-1,000 ohm resistor (or something close) put it into the circuit in place of the two electrodes. You should show current flow with the 9 volt battery between 9 and 90 milliamps on the multimeter (with the appropriate meter setting, say 200 mADC). That at least verifies that the wiring, battery and meter are working.

Good luck.

Rick Marz